The present invention relates to pressure regulating valves for feeding modules, for example for regulation of a system pressure.
A pressure regulating valve of the above mentioned general type is known in the art. It is disclosed for example in the German patent document DE 196 34 899 81. A valve chamber of this pressure regulating valve is provided with an inlet and with a control chamber connected through a valve opening with a valve chamber. A valve member is loaded with a valve closing spring which has an adjustable spring force. The valve member is pressed by means of the valve closing spring to a valve seat which surrounds the valve opening. For compensation of the spring force increase, during a growing outflow quantity downstream of the valve opening a throttle surface is arranged. The throttle surface is arranged so that, between the valve member and the control chamber, at the valve member a pressure which is dependent on the throughflow counteracts the spring force of the closing spring.
The known arrangement has a relatively great structural space, and thereby the throttle surfaces are quite expensive. This involves an expensive manufacturing process, which unavoidably increase the manufacturing cost.
Accordingly, it is an object of present invention to provide a pressure regulating valve for a feeding module, which avoids the disadvantages of the prior art.
In accordance with the present invention the valve member in accordance with the load condition of an internal combustion engine releases the throttle opening toward the return conduit in correspondence with its stroke path.
In addition to the cost-favorable realization of the pressure regulation on a fuel feeding module, with the inventive solution a flat up to a negative characteristic line increase is realized after the opening point of the pressure regulating valve. Depending on the construction of the throttle opening around the valve body, a flat characteristic line increase or a negative characteristic line increase is obtained, which takes into consideration individual customer requirements.
In accordance with a preferable embodiment of the inventive solution, the closing spring which loads the valve member has a spring characteristic line as a function of the supply pressure applied to the valve member. The closing spring is supported at one end against a pressure element which is movable relative to the valve body and on the other hand against a valve member which is cup-shaped. The valve member in turn is arranged moveably in the bucket-shaped valve body relative to the latter.
For variable adjustment of the spring force acting on the valve member, the cover element can move relative to a valve body. Thereby the pretensioning of the spring member can be increased or reduced. In addition to the thread which is provided in a connection region between the cover element and the valve body and which makes possible a rotary connection between the cover element and the valve body, also a bajonet lock can be provided. It can engage in different resting positions on the periphery of the cover element or valve body. In addition to the formation of a thread with a greater or smaller thread pitch in the connecting region, also a clamping connection can be provided, which makes possible any relative position between the valve body and the valve member.
The throttle opening can be slot-shaped in an advantageous manner. It can be also formed as a borehole in the valve body. In addition to the design of the throttle opening as a slot or a borehole, the throttle opening can be also composed of two or several adjoining slots or boreholes. The return conduit can be connected to the throttle opening in the flowout region of the pressure regulating valve, to return the fuel again to the fuel tank.
In accordance with an advantageous embodiment of the solution proposed in the invention, the valve body can surround the valve member in a cup-shaped manner, so that a very compact construction of the pressure regulating valve is provided.
In accordance with another feature of present invention a method of regulation of a fuel feeding module is provided, in accordance with which a valve member performs a stroke in dependence on supply pressure which releases the cross-section in the throttle opening in a flowout region of the pressure regulating valve so that, after an opening point of the pressure regulating valve a flat to a negative characteristic line increase of the pressure regulating valve is provided.
With the method in accordance with the present invention, with the supply pressure-dependent actuation of a valve member, the stroke path of the valve member can be varied, so that the cross-section of the throttle opening, depending on loading condition of the internal combustion engine is released, after the opening point of the pressure valve is exceeded, and thereby a flat characteristic line, or depending on the design of the throttle opening, a negative characteristic line increase is produced.
The throttling at the throttle opening drops lower with an increase of feeding quantity through the pressure regulator during idle running. The throttling at the throttling opening is increased depending on the reduction of the feeding quantity through the pressure regulating valve during full load of the internal combustion engine, since only a small quantity of fuel can flowout through the throttle opening in the supply tank.
The novel features which are considered as characteristic for the present invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.